1. Field of the Invention
This invention relates to low foam and foam depressing surfactant mixtures of water soluble and/or water emulsifiable polyalkylene glycol ethers of relatively long chain alcohols.
2. Statement of Related Art
Institutional and industrial aqueous cleaning preparations, particularly those intended for cleaning metal, glass, ceramic, and plastic surfaces, generally contain compounds which are capable of counteracting undesirable foaming. In most cases, the use of low-foam or foam-depressing surfactant-containing auxiliaries is necessitated by the fact that the various types of soil detached from the substrates to be cleaned and accumulating in the cleaning baths act as foam generators. This is particularly true for high-speed washing machines, for example bottle-washing machines, or in applications where the cleaning liquor is sprayed under high pressure onto the surfaces to be cleaned, for example, in spray cleaning.
Adducts of alkylene oxides with organic compounds containing reactive hydrogen atoms--preferably several reactive hydrogen atoms--in the molecule have long been successfully used as low-foam or foam-depressing additives with surfactant-like activity. Particularly good results have been obtained in practice with adducts of propylene oxide with aliphatic polyalcohols (cf. U.S. Pat. No. 3,491,029 and G.B. No. 1,172,135) and with polyamines (cf. U.S. Pat. No. 3,463,737 and G.B. No. 1,172,134) and with adducts of ethylene oxide and propylene oxide with aliphatic polyamines, particularly ethylenediamine (cf. U.S. Pat. No. 3,696,057). In addition to their favorable foam-suppressing or foam-depressing effect, alkylene oxide adducts such as these also show the alkali stability generally required for use in institutional and industrial cleaning preparations. Unfortunately, compounds of this class are not sufficiently biodegradable to meet the legal requirements of environmental protection legislation.